You know how, usually, when you surf the Web you can always
backpage to where you just were. But some sites seem to burn the bridge, as it were, when you surf to them, so you
can’t backpage to the previous site. How is this done, and
what is the terminology for it?
I believe they accomplish that thusly:
A meta refresh tag is something that can automatically send the user on to a new page after a certain length of time, and the user can’t control when it happens or where they go next (naturally). My guess is that on pages where hitting “Back” doesn’t work, what’s happened is that on the index page of that site, there is a meta refresh tag set for, say, 1 second (or less). So you’ll arrive at the index page and immediately be sent on to another page. When you hit “Back,” you’re just going back to that meta refresh tag, which sends you forward again, and keeps booting you forward no matter how often you hit back. You may not even see the page with the meta refresh tag, if it’s set for a small enough amount of time.
In case you’re curious, here’s what the code looks like:
<meta http-equiv=“refresh” content=“30; url=main.htm”>
The content= is the length of time, in seconds, until the user gets sent to another page. The url= is the address of the page they’ll get sent to.
I’ve seen this action before, specifically on http://www.imdb.com .
It’s not the meta refresh that does this, but I don’t know what it is.
When a page loads, the back button specifically disables, so even going back to a meta refresh page is impossible.
Annoying as this is, the more annoying thing is pages that do auto-popups on entering and/or leaving. Sometimes the popups reference the first page, then you have an endless loop of pages being generated.
This is a new trick used by some purveyors to increase the chances of you buying something at their website. Supposedly Eddie Bauer and several other major etailers are using this strategy.
All I can say is that if you ever wished for a better way to piss off web customers, I’d be hard pressed to think of one. Personally, I hope that every single site that employs this technique is boycotted in droves.
Such interference in the operation of one’s computer is intolerable and must meet with the harshest calumny from the online population!
Whenever I get one of those windows, I thwart its evil purpose – not by clicking on the back button, but by holding down the back button. Eventually a menu appears, with the pages in recent history. You can just leapfrog over the offending pages and back to where you were before the trap was sprung.
On Netscape 4.* you just hold down the whole back button. On IE 5.* there’s a sliver down the right edge of the back button that gives you the recent history menu.
If you go to a site, and your Back button is suddenly disabled (as opposed to being able to click on the back button, only to be sent to the exact same page), this means that the site includes Javascript code that has changed your “history”.
Each browser has a history object that lists all the sites you have previously visited. They are indexed, with “window.history[0]” being the first site you visited. Code in Javascript can change it so that the site you are currently on is then positioned as the 0-indexed site. Then, your browser sees the site as the first one you have visited, so you have nothing to go back to.
I think (but I’m not sure) that its also possible to have code actually erase all the listings in your history object.
Yes. Javascript has control of the history list, and the usual ruse is to use it to place the current page on the history list so that the back button backs up to it.
I think the phenomenon the OP was referring to was the meta-refresh issue, though, amply explained by Beadalin.
As somebody who has been concerned with the other side, ie. app servers, I can tell you that browser navigation issues are a major cause of headaches in developing any web-based application which requires session-maintained data.
The stunt with the back button so that you can’t “escape” a site is cheesy, if that’s your reason for doing it. There are, however, other application areas for which it would be really nice to control navigation within the application.
Things like corporate HR and decision support applications are now being enabled through web interfaces, and these are things that normally require you to do a several-page interaction with the user, and maintain very intricate transaction states with large databases on the server side (I’m using the term loosely. Nobody in their right mind leaves an actual DB transaction open across web events). The fact that the browser can back the user up to any previous display, for which your current server-side state is likely to be incompatible, is a big pain in the rear end. Some applications just do not lend themselves well to stateless presentation, and the state info is WAY too large to be maintained with the pages themselves and WAY too complex too allow you to assure arbitrary recovery of an earlier state.
Even storefront sites with relatively simple interactions have enormous problems in this area.
Early on, somebody tried to suggest a “kiosk” mode for sites which wished to control navigation through their pages. Those pages would not have been added to the browser history, and the browser would only let you navigate to previous “non-kiosk” pages, and would be able to make it clear to you that the application wished you to navigate within it only by means of the links presented on the pages themselves. I do wish that suggestion had gotten industry traction.
It seems like people have already answered the OP.
Thought I’d add that when clicking on a “link” I open up a new browser window if I think there’s a chance I might want to go back. This is often faster, and makes it easier to avoid getting trapped – you just close the window.
Yep, it’s a javascript trick. There are two ways to defeat this.
- Turn off Javascript in your browser prefs before surfing the site.
- Go to a new URL outside that site. Your history list will be restored to function. Now hold down the BACK button until your history list appears. Go back 2 sites in one move, skip the offending site.
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- I asked aboout this some time back and nobody seemed to know what I was describing. I have only seen porn sites do it. Your back button is disabled and the history only shows that site that you’re on. You can either press the “home” button or shut down your browser. Neither helps whe you’ve wandered through a bunch of links to get where you’re at. - MC
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